{
  "id": "2206.03503",
  "version": "v1",
  "published": "2022-06-07T18:00:01.000Z",
  "updated": "2022-06-07T18:00:01.000Z",
  "title": "The ISM of high-redshift galaxies: clues from C III] and [C II] lines",
  "authors": [
    "Vladan Markov",
    "Stefano Carniani",
    "Livia Vallini",
    "Andrea Ferrara",
    "Andrea Pallottini",
    "Roberto Maiolino",
    "Simona Gallerani",
    "Laura Pentericci"
  ],
  "comment": "16 pages, 13 figures, to be published in A&A",
  "categories": [
    "astro-ph.GA"
  ],
  "abstract": "A tight relation between [C II] $ 158 \\ {\\rm{\\mu m}}$ line luminosity and star formation rate (SFR) is observed in local galaxies. At $z > 5$, galaxies instead deviate downwards from the local $\\Sigma_{\\rm{[C II]}}-\\Sigma_{\\rm{SFR}}$ relation. This deviation might be caused by different interstellar medium (ISM) properties in galaxies at early epochs. We combine the [C II] and SFR data with C III] $\\lambda1909$ line observations and our physical models. We additionally investigate how the ISM properties: burstiness $\\kappa_s$, total gas density $n$, and metallicity $Z$, affect the deviation from the $\\Sigma_{\\rm{[C II]}}-\\Sigma_{\\rm{SFR}}$ relation in these sources. We present the VLT/X-SHOOTER observations targeting the C III] $\\lambda1909$ line emission in three galaxies at $5.5<z<7.0$. We extend our sample of galaxies by including archival X-SHOOTER and MUSE data of eight sources at $2<z<7$ and eleven star-forming systems at $6 < z< 7.5$ with C III] or [C II] data reported in the literature. We detect C III] $\\lambda \\lambda1907, 1909$ line emission in HZ10 and derive the intrinsic flux of the C III] $ \\lambda1909$ line. We constrain the ISM properties of our sample of galaxies: $\\kappa_s$, $n$, and $Z$, by applying our physically motivated model based on the MCMC algorithm. For the most part, high-$z$, star-forming galaxies show subsolar metallicities. The majority of the sources have $\\log{(\\kappa_s)} \\gtrsim 1$, i.e., they overshoot the Kennicutt-Schmidt relation by about one order of magnitude. This suggests that the whole KS relation might be shifted upwards at early times. Next, all the high-$z$ galaxies of our sample lie below the $\\Sigma_{\\rm{[C II]}}-\\Sigma_{\\rm{SFR}}$ local relation. The total gas density $n$ shows the strongest correlation with the deviation from the local $\\Sigma_{\\rm{[C II]}}-\\Sigma_{\\rm{SFR}}$ relation, in agreement with theoretical models.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2022-06-07T18:00:01.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "high-redshift galaxies",
      "total gas density",
      "line emission",
      "ism properties",
      "star formation rate"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 16,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}